Emotional pictures engage attention, as measured by traditional indices of resource allocation such as the magnitude and duration of startle blink inhibition, the amplitude of the P3 component to a secondary startle probe, and the amplitude of the late positive potential during affective picture processing. Two hypotheses exploring the role of attention in emotion are tested here: the motivated attention hypothesis holds that when affective cues activate basic biphasic motivational systems, attention is automatically mobilized, producing an oriented, attentive set. The perceptual encoding hypothesis views attentional effects in emotion as resulting from differences in stimulus complexity, familiarity or novelty, particularly as these impact the initial encoding (i.e., identification) stage. A number of critical tests of these two hypotheses are presented, which will allow us to determine the role of attention in emotional processing. A series of psychophysiology experiments are proposed that use the probe-timing paradigm, in which startle probes are presented at various intervals after picture onset (or offset). Three primary dependent measures are used to assess effects of manipulated variables on attention and emotion: The elicited startle blink and the startle probe ERP will be used to track attention and emotion across time; picture onset ERPs will be used to index changes in picture encoding processes. In Years 4-these paradigms will be brought into the fMRI domain to identify structures associated with attention in emotional processing. Taken together, the basic science studies proposed here will elucidate the extent to which activation of basic motivational systems automatically directs attention and the extent to which affective processing is mediated by secondary factors of stimulus complexity, novelty, or familiarity. These data will provide a foundation for exploring and understanding emotional and attentional deficits in populations suffering mental-health or neurological problems.